The present invention relates to a non-return valve for a fuel tank.
Such a valve is mounted in the tube used for filling the tank, firstly to prevent the fuel present in the tank from being expelled in the event of the pressure inside the tank being raised, and secondly to reduce the risk of leakage in the event of an accident that causes the filler tube to be broken.
The present invention provides a novel non-return valve which is reliable and of relatively low cost to produce.
The non-return valve of the invention comprises a substantially tubular body and a deformable shutter member fixed to said body, said shutter member being formed integrally by molding a plastics material, that can possibly be an elastomer, and being shaped in such a manner as to return under its own elasticity into a shut position, with the valve body serving as a seat, whenever the shutter member is at rest and the pressure of fuel is no longer sufficient to overcome the elastic return action of the shutter member.
In a particular embodiment, the valve body is provided with at least one axial inlet orifice and with at least one lateral outlet orifice.
Still in a particular embodiment, the shutter member comprises a substantially rigid, shutter-forming portion that is movable inside the valve body, and at least one spring-forming, flexible strip for returning said substantially rigid portion into the shut position. Said flexible strip may extend substantially helically or in a zigzag.
In another particular embodiment, the shutter member comprises a substantially rigid, shutter-forming portion that is movable inside the valve body, and at least one spring-forming bellows for returning said substantially rigid portion into the shut position. Advantageously, said bellows is held in place by a retaining member comprising a base designed to be snap-fastened to the valve body and by a perforated thimble extending inside the bellows.
In another particular embodiment, the valve has a body that is substantially tubular, provided with an axial inlet orifice and with an axial outlet orifice, and the shutter member includes a flap organized at rest to shut the outlet orifice, said flap being secured to at least one flexible, spring-forming tab organized to return it into the shut position. The flap preferably has an extension hinged to the valve body.
In another particular embodiment, the shutter member has a flexible membrane which, at rest, has the shape of a spherical cap, the concave side thereof facing towards the filler tube, said flexible membrane being fixed to the valve body via a flexible central stud.
Preferably, at rest, the periphery of the membrane rests against one end of the valve body.